1. Field of the Invention
This invention relates to polymeric antioxidants. In particular, it relates to novel polymeric phenolic antioxidants and their preparation.
2. The Prior Art
Phenolic compounds are known to be useful as antioxidants, stabilizing substrates such as petroleum products, resins, rubber, and in certain instances, foodstuffs. To find successful application as a foodstuff antioxidant, a phenolic material must be nontoxic, in addition to providing protection against oxidation.
Several phenolics have been used as antioxidants in foodstuffs, including butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA). These compounds have not been wholly satisfactory for a variety of reasons. They are high in cost and lack sufficient "carry through"; that is, their inhibitory action is not carried through into finished food products, as for example, into baked goods, to a desired degree. Furthermore, toxicity questions have been raised which are serious enough to result in BHT and BHA's use being restricted in the United States and prohibited in some European countries.
Finding safe alternatives is difficult. When any phenolic is ingested and absorbed from the gastrointestinal tract into the body, toxicity problems are raised, since many phenolic derivatives are toxic and the exact products of phenolic metabolism are not well known or fully predictable.
These problems are overcome, however, when an antioxidant is employed which has a molecular size which prevents its being absorbed through the walls of the gastrointestinal tract. It is such an antioxidant and its preparation to which this invention relates-- a polymeric antioxidant which may be easily varied in molecular size to achieve the desired nonabsorption through the walls of the gastrointestinal tract. The antioxidants of this invention also find use in non-food applications, where their high molecular weight leads to low volatility and improved carry-through properties.